Certain firearms, such as certain semi-automatic and automatic firearms in the family of AR-15/M16 firearms, may include a tubular handguard which surrounds at least a portion of the length of the barrel.
Among other functions, the handguard may protect the firearm operator's hand from a heated barrel after the firearm is fired, particularly by inhibiting the operator's hand from contacting the barrel directly and subsequently suffering a burn or other injury. The handguard may also protect the barrel and other parts of the firearm contained therein from being damaged during use of the firearm.
The handguard may be made of metal, particularly aluminum. However, in response to extreme use of the firearm, a metal handguard may be understood to heat-up due to the high thermal conductivity of the metal, and thus defeat the objective of protecting the firearm operator's hand from heat associated with the barrel after the firearm is fired.
In order to address the problems associated with the heating of metal handguards, injection molded thermoplastic polymer handguards have been developed. However, while addressing the problems associated with the heating of metal handguards, the injection molded thermoplastic polymer may not offer adequate strength or other physical properties, such as impact resistance or heat resistance.
In order to increase either the impact resistance and/or heat resistance of an injection molded thermoplastic polymer, fiber reinforcement may be added to the injection molded thermoplastic polymer to provide a fiber-reinforced thermoplastic handguard.
However, a fiber-reinforced thermoplastic polymer, while possibly offering an increase in impact resistance and heat resistance as compared to an unreinforced thermoplastic polymer, still may suffer from impact resistance and heat resistance limitations as the fiber length of injection molded fiber reinforced thermoplastic polymers is generally less than 10 mm, and more commonly less than about 3 mm, due to the screw of the injection molding machine tending to break the fibers as they are processed within the barrel. Furthermore, fiber loading levels may generally be limited to about 20-30% by weight.
Many handguards also require custom mounting, which requires modification of the firearm in order to install the handguard.